Add demo app

[captainbarbosa]

✨ Workin on it ✨

[captainbarbosa]

I'm going to leave the features introduced from #43 for a separate PR.

[fabian-guerra]

This looks good! I have two main architecture observations:

For delegate implementations try to follow the pattern:

extension ClassName: DelegateName {
...
}

When returning the updated view, avoid using willMove and move that logic to the controller.

I found two bugs:

In the line style annotations when you pick a different color then close then chose again the annotation it resets the previous selected value.

On non iPhone X phones the content insets at the bottom are wrong.

[captainbarbosa]

In the line style annotations when you pick a different color then close then chose again the annotation it resets the previous selected value.

@fabian-guerra I pulled in #47 in 1341b3f which fixes this issue.

[fabian-guerra]

This looks good, and almost done. There are three remaining issues:

1. If you select the label and change only the font color it changes the icon color too.
2. If you select one annotation then select another then hold and drag the previous annotation it duplicates that annotation.
3. Is not possible to change the icon rotation in non iPhoneX phones.

[captainbarbosa]

Issues 1 & 3 are fixed in 0241c01, and 2 will resolve itself once #48 merges and is pulled back into this branch.

[fabian-guerra]

Thank you.